Optical transceiver modules are crucial for high-speed data transfer in modern communication. This article explores their components, working principles, parameters, types, and uses in data centers, enterprises, and telecoms. They're key to the information age.
Components and Working Principles
An optical transceiver consists of a transmitter, receiver, drive circuit, control circuit, and optical fiber interface. Its working principle is to drive the laser through the electrical signal at the transmitter end, convert the electrical signal into an optical signal, and after transmission through the optical fiber, the photodetector at the receiving end converts the optical signal back into an electrical signal to achieve high-speed data transmission.
Key technical parameters
(1) Data Rate
The transmission rate refers to the amount of data that an optical transceiver can transmit per second, usually measured in Gbps (gigabits per second). Common rates are: 10 Gbps, 25 Gbps, 40 Gbps, 100 Gbps, 400 Gbps, 800 Gbps.
(2) Transmission Distance
The transmission distance refers to the physical distance at which an optical transceiver can stably transmit data on an optical fiber, usually expressed in meters or kilometers.
Common Transmission Distance Classifications:
- SR (Short Range), generally less than 300 meters.
- DR (Data Center Range), nearly 500 meters.
- LR (Long Range), more than 10 km.
- ER (Extended Range), up to 40 km and above.
- ZR (Zero Replacement Range), can support up to 80 or even 100 km.
(3) Wavelength
The wavelength (unit: nm, nanometer) used by an optical transceiver determines its transmission characteristics. The choice of different wavelengths depends on the transmission distance and the environment in which they are used:
- 850nm: Typically used for multimode fibers, suitable for short-distance transmission.
- 1310nm: used for single-mode fiber, suitable for medium and long-distance transmission (generally within 10 km).
- 1550nm: for single-mode fiber, suitable for long-distance transmission (more than 10 km).
Fiber Mode
- MMF, Multimode FiberIt is suitable for short-distance (e.g., up to 100 meters) transmission and has a low cost.
- SMF, Single Mode FiberSuitable for long-distance (e.g., more than 10 km) transmission, with higher bandwidth and lower attenuation.
Classification and its scope of application
(1) Form Factor
The form factor of an optical transceiver determines its shape and connection method, and various package types are suitable for different device interfaces and usage scenarios:
- SFP (Small Form-factor Pluggable): It supports 1G or 10G and is widely used in enterprise networks and small data centers. It supports 1G or 10G and is widely used in enterprise networks and small data centers.
- SFP+: An upgraded version of SFP that supports 10G speeds and is commonly used in data centers and Fiber Channel applications.
- QSFP (Quad Small Form-factor Pluggable): It supports 40G speed and has high port density, which is suitable for high-density data centers.
- QSFP+: It supports higher speeds, such as 40G and 100G, and is widely used in Ethernet and high-performance computing.
- QSFP28: Suitable for 100G speeds with higher data density, it is ideal for data centers with high bandwidth requirements.
- QSFP-DD (Quad Small Form-factor Pluggable Double Density): It supports 400G speeds, making it suitable for large-scale data centers and AI clusters, providing higher density and efficiency.
- OSFP (Octal Small Form-factor Pluggable): It supports 400G and 800G speeds, and is mainly used in high-speed data centers.
(2) Data Rate
Optical transceivers are divided into different categories according to the transmission rates they support to meet the needs of various networks:
- 1G/10G: The standard rate in early networks, widely used in enterprise networks and low-traffic data centers.
- 25G: Increases bandwidth while keeping power consumption low, making it ideal for smaller data centers.
- 40G/100G: Mainstream high-performance data center speeds to meet the needs of medium and large enterprises and cloud computing platforms.
- 200G/400G: The mainstream choice for large-scale data centers and AI clusters, providing extremely high bandwidth and throughput, and supporting massively parallel computing.
- 800G: The latest rate standard for ultra-large-scale AI clusters and high-bandwidth scenarios, such as AI supercomputing centers and telecom operators' core networks.
(3) Wavelength
The wavelength selection of an optical transceiver not only determines the transmission distance, but also affects the type of fiber it uses:
- 850nm: The standard wavelength of multimode fiber, suitable for short-distance transmission within 300 meters.
- 1310nm: The mainstream wavelength of single-mode fiber, suitable for medium and long-distance transmission, widely used for connection between data centers.
- 1550nm: Used for longer-distance, single-mode fiber transmission, especially in telecom backbone networks and long-distance transmission scenarios.
(4) Fiber Mode
The fiber mode determines the transmission medium and distance of the optical transceiver:
- Multimode fiber (MMF): Suitable for short-distance, high-density scenarios, the transmission distance is usually between 100 meters and 300 meters, and is widely used in data centers.
- Single-mode fiber (SMF): Suitable for long-distance transmission up to 10 kilometers or more, suitable for connections between data centers, metro networks, and backbone networks.
(5) Transmission Distance
Optical transceivers can travel over a wide range of distances, from short-haul data centers to cross-metro backbone networks:
Short distance (<300 meters): Multimode fiber is suitable for connections, typically used within data centers.
Medium distance (1-10 km): Single-mode fiber is suitable for interconnection between data centers.
Long distance (> 10 km): Single-mode fiber is suitable for telecom networks and metro networks.
Applications
- Data Centers. Data centers are one of the main application scenarios of optical transceivers. With the explosive growth of AI, cloud computing, and big data, the demand for high-speed and low-latency networks is increasing, and 400G and 800G optical transceivers have become the standard configuration of large-scale data centers and AI clusters, which can effectively improve data throughput and system response speed to meet the needs of complex computing and data storage.
- Enterprise networking. Optical transceivers for enterprise networks are mainly used for high-speed interconnection between different office locations. The common rate is 10G, 25G, or 40G, which is suitable for the backbone interconnection of small data centers and enterprise networks to ensure the smooth transmission of data between various departments.
- Storage networking. Storage networks require high-speed and reliable data transmission, and Fibre Channel (FC) is the dominant technology in storage networks. Optical transceivers provide high-bandwidth connectivity to servers and storage devices, enabling efficient operation of storage systems at speeds ranging from 8 Gbit/s to 32 Gbit/s.
- Telecommunications Networks. The application of optical transceivers in the telecommunications industry is concentrated in metro networks, wide area networks and backbone networks to provide long-distance and high-speed data transmission services.
